Question

question
suppose that a 25 °c solution has a poh of 8.6. what is the concentration of hydronium ions?
select the correct answer below:
2.512×10⁻⁹ m
3.981×10⁻⁶ m
1.841×10⁻⁴ m
4.517×10⁻³ m

Explanation:

Step1: Calculate pH

At \(25^{\circ}\text{C}\), \(pH + pOH=14\). Given \(pOH = 8.6\), then \(pH=14 - 8.6=5.4\).

Step2: Calculate \([H_3O^+]\)

The formula for \(pH\) is \(pH=-\log[H_3O^+]\). Rearranging for \([H_3O^+]\), we get \([H_3O^+]=10^{-pH}\). Substituting \(pH = 5.4\), \([H_3O^+]=10^{-5.4}\). Using the property \(a^m=a^{n + k}=a^n\times a^k\) (\(5.4 = 6-0.6\)), \(10^{-5.4}=10^{-(6 - 0.6)}=\frac{10^{0.6}}{10^{6}}\). Since \(10^{0.6}\approx3.981\), \([H_3O^+]=\frac{3.981}{10^{6}} = 3.981\times10^{-6}\text{ M}\).

Answer:

B. \(3.981\times10^{-6}\text{ M}\)